In this paper, by carrying out a small pilot study it is tested that vocabulary selection based on word family is useful for Korean vocabulary teaching and learning. As a result of applying Nation`s ``word family`` to word analyzed corpus (elementary text books) the number of vocabulary dropped to 80% of what it was based on basic word form. Main components of building large word family are 2-syllable noun of Chinese orgin. As for text coverage, 5,625 word families can cover 95% of the text. And on the point of the text coverage 98%, the number of vocabulary based on word family is about 3,000 smaller than basic word form. A lot of prior questions for vocabulary selection based on word family were discovered during this study. If the criteria for vocabulary selection based on word family is fixed, we can develop the program making word family list for individual user.